In general, among technologies to form various thin films on a substrate or a wafer, a CVD (Chemical Vapor Deposition) scheme has been extensively used. The CVD scheme results in a chemical reaction. According to the CVD scheme, a semiconductor thin film or an insulating layer is formed on a wafer surface by using the chemical reaction of a source material.
The CVD scheme and the CVD device have been spotlighted as an important thin film forming technology due to the fineness of the semiconductor device and the development of high-power and high-efficiency LED. Recently, the CVD scheme has been used to deposit various thin films, such as a silicon layer, an oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a tungsten layer, on a wafer.
For example, to deposit a silicon carbide thin film on a substrate or a wafer, a reactive raw material capable of reacting with the wafer needs to be introduced. According to the related art, a silicon carbide epitaxial layer is deposited by introducing silane (SiH4) and ethylene (C2H4) serving as a standard precursor or methyltrichlorosilane (MTS) as a raw material, heating the raw material to produce an intermediate compound such as CH3 or SiClx, and introducing the intermediate compound to react the intermediate compound with a wafer disposed in a susceptor.
However, carbon and silicon are not uniformly distributed on a surface of the wafer on which the silicon carbide epitaxial thin film layer is deposited but the silicon is highly distributed on the surface of the wafer. In this case, since the silicon increases surface roughness of the wafer, the silicon may cause a defect in the epitaxial wafer.
Therefore, a method capable of modifying a surface of the silicon carbide wafer is required.